Semiconductor die structure with air gaps and method for preparing the same

ABSTRACT

The present disclosure provides a semiconductor die structure with air gaps for reducing capacitive coupling between conductive features and a method for preparing the semiconductor die structure. The semiconductor die structure includes a substrate; a first supporting backbone disposed on the substrate; a second supporting backbone disposed on the substrate; a first conductor block disposed on the first supporting backbone; a second conductor block disposed on the second supporting backbone; a third conductor block disposed above the substrate and connected to the first conductor block and the second conductor block; and an air gap structure disposed between the first conductor block, the second conductor block, and the third conductor block, wherein the air gap structure comprises an air gap and a liner layer enclosing the air gap.

TECHNICAL FIELD

The present disclosure relates to a semiconductor die structure and amethod for preparing the same, and more particularly, to a semiconductordie structure with air gaps for reducing capacitive coupling betweenconductive features and a method for preparing the same.

DISCUSSION OF THE BACKGROUND

Semiconductor dies are widely used in electronics industries.Semiconductor dies may have relatively small sizes, multi-functionalcharacteristics, and/or relatively low manufacture costs. Semiconductordies may be categorized as any one of semiconductor memory dies storinglogical data, semiconductor logic dies processing logical data, andhybrid semiconductor dies having both the function of the semiconductormemory dies and the function of the semiconductor logic dies.

Relatively high-speed and relatively low-voltage semiconductor dies maysatisfy desired characteristics (e.g., high speed and/or low powerconsumption) of electronic dies including semiconductor dies.Semiconductor dies may be relatively highly integrated. Reliability ofsemiconductor dies may be reduced by relatively high integration densityof the semiconductor dies.

This Discussion of the Background section is provided for backgroundinformation only. The statements in this Discussion of the Backgroundare not an admission that the subject matter disclosed in this sectionconstitutes prior art to the present disclosure, and no part of thisDiscussion of the Background section may be used as an admission thatany part of this application, including this Discussion of theBackground section, constitutes prior art to the present disclosure.

SUMMARY

One aspect of the present disclosure provides a semiconductor diestructure, comprising: a substrate; a first supporting backbone disposedon the substrate; a second supporting backbone disposed on thesubstrate; a first conductor block disposed on the first supportingbackbone; a second conductor block disposed on the second supportingbackbone; a third conductor block disposed above the substrate andconnected to the first conductor block and the second conductor block;and an air gap structure disposed between the first conductor block, thesecond conductor block, and the third conductor block, wherein the airgap structure comprises an air gap and a liner layer enclosing the airgap.

In some embodiments, the semiconductor die structure further comprises afirst metal cap disposed on the first conductor block and a second metalcap disposed on the second conductor block.

In some embodiments, the first metal cap and the second metal capcomprise a metal silicide.

In some embodiments, the metal silicide comprises cobalt (Co), copper(Cu), ruthenium (Ru), cobalt monosilicide (CoSi), or nickelmono-silicide (NiSi).

In some embodiments, the third conductor block is suspended over the airgap structure.

In some embodiments, the first conductor block and the second conductorblock are separated by the air gap structure.

In some embodiments, the first supporting backbone and the secondsupporting backbone are separated by the air gap structure.

In some embodiments, the first supporting backbone and the secondsupporting backbone comprise a tungsten oxide, a hafnium oxide, azirconium oxide, silicon mononitride (SiN), silicon carbide (SiC),silicon carbonitride (SiCN).

Another aspect of the present disclosure provides a semiconductor diestructure, comprising: a substrate including a first site and a secondsite; a first conductor block disposed on the first site; a secondconductor block disposed on the second site; a third conductor blockdisposed above the substrate and connected to the first conductor blockand the second conductor block; an air gap structure disposed betweenthe first conductor block, the second conductor block, and the thirdconductor block, wherein the air gap structure comprises an air gap anda liner layer enclosing the air gap.

In some embodiments, the semiconductor die structure further comprises afirst metal cap disposed on the first conductor block and a second metalcap disposed on the second conductor block.

In some embodiments, the first metal cap and the second metal capcomprise a metal silicide.

In some embodiments, the metal silicide comprises cobalt (Co), copper(Cu), ruthenium (Ru), cobalt monosilicide (CoSi), or nickelmono-silicide (NiSi).

In some embodiments, the third conductor block is suspended over the airgap structure.

In some embodiments, the first conductor block and the second conductorblock are separated by the air gap structure.

Another aspect of the present disclosure provides a method for preparinga semiconductor die structure, comprising: forming a first supportingbackbone on the substrate; forming a first conductor block on the firstsupporting backbone; forming a second supporting backbone on thesubstrate; forming a second conductor block on the second supportingbackbone; forming a third conductor block suspended above the substrateand connected to the first conductor block and the second conductorblock; sequentially forming an energy removable layer and a cappingdielectric layer over the substrate, and the energy removable layer andthe capping dielectric layer separating the first conductor block, thesecond conductor block and the third conductor block; and performing aheat treatment process to transform the energy removable layer into aplurality of air gap structures, wherein at least one of the air gapstructures comprises an air gap and a liner layer enclosing the air gap.

In some embodiments, the forming of the first supporting backbone on thesubstrate comprises: forming a plurality of silicon-containing lines onthe substrate; depositing a spacer layer on the substrate and theplurality of silicon-containing lines; and removing a first portion ofthe spacer layer to expose a first portion of the substrate between theplurality of polysilicon lines.

In some embodiments, the forming of the first conductor block on thefirst supporting backbone comprises forming a metal capped with a firsthard mask between the plurality of silicon-containing lines.

In some embodiments, the forming of the second supporting backbonecomprises: removing the plurality of polysilicon lines; forming thespacer layer on the substrate; and removing a second portion of thespacer layer to expose a second portion of the substrate.

In some embodiments, the forming of the second conductor block on thesecond supporting backbone comprises forming the metal capped with asecond hardmask.

In some embodiments, the forming of the third conductor block above thesubstrate further comprises removing the spacer layer.

Embodiments of the semiconductor die structure are provided in thedisclosure. The semiconductor die structure includes a plurality of airgaps, and the conductor blocks are separated from the each other by theair gaps. Therefore, the parasitic capacitance between the conductivecontacts may be reduced. As a result, the overall device performance maybe improved (i.e., the decreased power consumption andresistive-capacitive (RC) delay), and the yield rate of thesemiconductor device may be increased.

The foregoing has outlined rather broadly the features and technicaladvantages of the present disclosure in order that the detaileddescription of the disclosure that follows may be better understood.Additional features and advantages of the disclosure will be describedhereinafter, and form the subject of the claims of the disclosure. Itshould be appreciated by those skilled in the art that the conceptionand specific embodiment disclosed may be readily utilized as a basis formodifying or designing other structures or processes for carrying outthe same purposes of the present disclosure. It should also be realizedby those skilled in the art that such equivalent constructions do notdepart from the spirit and scope of the disclosure as set forth in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It shouldbe noted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a method for fabricating a semiconductor structurewith air gaps for reducing capacitive coupling between conductivefeatures such as lines and wires according to some embodiments of thepresent disclosure.

FIG. 2 is cross-sectional views illustrating an intermediate stage inthe formation of the semiconductor die structure, in accordance withsome embodiments of the present disclosure.

FIG. 3 is a cross-sectional view illustrating an intermediate stage offorming a carbon hard mask in the formation of the semiconductor diestructure, in accordance with some embodiments of the presentdisclosure.

FIG. 4 is a cross-sectional view illustrating an intermediate stage offorming a spacer opening in the formation of the semiconductor diestructure, in accordance with some embodiments.

FIG. 5 is a cross-sectional view illustrating an intermediate stage offorming the supporting backbone in the formation of the semiconductordie structure, in accordance with some embodiments of the presentdisclosure.

FIG. 6 is a cross-sectional view illustrating an intermediate stage offorming a conductor block in the formation of the semiconductor diestructure, in accordance with some embodiments of the presentdisclosure.

FIG. 7 is a cross-sectional view illustrating an intermediate stage ofperforming a planarization process in the formation of the semiconductordie structure, in accordance with some embodiments of the presentdisclosure.

FIG. 8 is a cross-sectional view illustrating an intermediate stage ofperforming a recessing process in the formation of the semiconductor diestructure, in accordance with some embodiments of the presentdisclosure.

FIG. 9 is a cross-sectional view illustrating an intermediate stage offorming a metal silicide layer in the formation of the semiconductor diestructure, in accordance with some embodiments of the presentdisclosure.

FIG. 10 is a cross-sectional view illustrating an intermediate stage offorming a first hard mask in the formation of the semiconductor diestructure, in accordance with some embodiments of the presentdisclosure.

FIG. 11 is a cross-sectional view illustrating an intermediate stage ofperforming an etching process in the formation of the semiconductor diestructure, in accordance with some embodiments of the presentdisclosure.

FIG. 12 is a cross-sectional view illustrating an intermediate stage ofperforming an etching process in the formation of the semiconductor diestructure, in accordance with some embodiments of the presentdisclosure.

FIG. 13 is a cross-sectional view illustrating an intermediate stage ofperforming a deposition process in the formation of the semiconductordie structure, in accordance with some embodiments of the presentdisclosure.

FIG. 14 is a cross-sectional view illustrating an intermediate stage offorming a second supporting backbone in the formation of thesemiconductor die structure, in accordance with some embodiments of thepresent disclosure.

FIG. 15 is a cross-sectional view illustrating an intermediate stage offorming a conductor block in the formation of the semiconductor diestructure, in accordance with some embodiments of the presentdisclosure.

FIG. 16 is a cross-sectional view illustrating an intermediate stage offorming a second hard mask in the formation of the semiconductor diestructure, in accordance with some embodiments of the presentdisclosure.

FIG. 17 is a cross-sectional view illustrating an intermediate stage ofremoving the spacer layer in the formation of the semiconductor diestructure, in accordance with some embodiments of the presentdisclosure.

FIG. 18 is a cross-sectional view illustrating an intermediate stage offorming an energy removable layer and a capping dielectric layer in theformation of the semiconductor die structure, in accordance with someembodiments of the present disclosure.

FIG. 19 is a cross-sectional view illustrating an intermediate stage offorming air gaps and liner layers in the formation of the semiconductordie structure, in accordance with some embodiments of the presentdisclosure.

FIG. 20 is a schematic illustration of an exemplary integrated circuit,such as a memory device, including an array of memory cells inaccordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedie in use or operation in addition to the orientation depicted in thefigures. The apparatus may be otherwise oriented (rotated 90 degrees orat other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

It should be understood that when an element or layer is referred to asbeing “connected to” or “coupled to” another element or layer, it can bedirectly connected to or coupled to another element or layer, orintervening elements or layers may be present.

It should be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. Unless indicated otherwise, these terms areonly used to distinguish one element from another element. Thus, forexample, a first element, a first component or a first section discussedbelow could be termed a second element, a second component or a secondsection without departing from the teachings of the present disclosure.

Unless the context indicates otherwise, terms such as “same,” “equal,”“planar,” or “coplanar,” as used herein when referring to orientation,layout, location, shapes, sizes, amounts, or other measures, do notnecessarily mean an exactly identical orientation, layout, location,shape, size, amount, or other measure, but are intended to encompassnearly identical orientation, layout, location, shapes, sizes, amounts,or other measures within acceptable variations that may occur, forexample, due to manufacturing processes. The term “substantially” may beused herein to reflect this meaning. For example, items described as“substantially the same,” “substantially equal,” or “substantiallyplanar,” may be exactly the same, equal, or planar, or may be the same,equal, or planar within acceptable variations that may occur, forexample, due to manufacturing processes.

In the present disclosure, a semiconductor die generally means a diewhich can function by utilizing semiconductor characteristics, and anelectro-optic die, a light-emitting display die, a semiconductorcircuit, and an electronic die are all included in the category of thesemiconductor die.

It should be noted that, in the description of the present disclosure,above (or up) corresponds to the direction of the arrow of the directionZ, and below (or down) corresponds to the opposite direction of thearrow of the direction Z.

FIG. 1 illustrates a method 10 for fabricating a semiconductor structurewith air gaps for reducing capacitive coupling between conductivefeatures such as lines and wires according to some embodiments of thepresent disclosure. The method 10 may be performed as operations. It maybe noted that the method 10 may be performed in any order and mayinclude the same, more, or fewer operations. It may be noted that themethod 10 may be performed by one or more pieces of semiconductorfabrication equipment or fabrication tools. In some embodiments, themethod 10 includes steps S11, S13, S15, S17, S19, S21 and S23. The stepsS11 to S23 of FIG. 1 are elaborated in connection with followingfigures.

In some embodiments, referring to FIGS. 2-5, at the step S11 in themethod 10 shown in FIG. 1, fabrication processes are performed to form afirst supporting backbone 111 on a substrate 101.

In some embodiments, the substrate 101 may be a semiconductor wafer suchas a silicon wafer. Alternatively or additionally, the substrate 101 mayinclude elementary semiconductor materials, compound semiconductormaterials, and/or alloy semiconductor materials. Examples of theelementary semiconductor materials may include, but are not limited to,crystal silicon, polycrystalline silicon, amorphous silicon, germanium,and/or diamond. Examples of the compound semiconductor materials mayinclude, but are not limited to, silicon carbide, gallium arsenic,gallium phosphide, indium phosphide, indium arsenide, and/or indiumantimonide. Examples of the alloy semiconductor materials may include,but are not limited to, SiGe, GaAsP, AlInAs, AlGaAs, GalnAs, GaInP,and/or GaInAsP.

In some embodiments, the substrate 101 includes an epitaxial layer. Forexample, the substrate 101 has an epitaxial layer overlying a bulksemiconductor. In some embodiments, the substrate 101 is asemiconductor-on-insulator substrate which may include a substrate, aburied oxide layer over the substrate, and a semiconductor layer overthe buried oxide layer, such as a silicon-on-insulator (SOI) substrate,a silicon germanium-on-insulator (SGOI) substrate, or agermanium-on-insulator (GOI) substrate. Semiconductor-on-insulatorsubstrates can be fabricated using separation by implantation of oxygen(SIMOX), wafer bonding, and/or other applicable methods.

In some embodiments, the substrate 101 may be a variety of materials,including, but not limited to, sapphire, silicon, gallium nitride (GaN),germanium, or silicon carbide. The substrate 101 may be silicon oninsulator (SOI). In some embodiments of the present disclosure, thesubstrate 101 is silicon. crystallographic orientation of asubstantially monocrystalline substrate 101 may be any of (100), (111),or (110) on the Miller Indices. Other crystallographic orientations arealso possible. The crystallographic orientations of substrate 101 may beoffcut. In some embodiments of the present disclosure, the substrate 101is (100) silicon with crystalline substrate surface region having cubiccrystallinity. In another embodiment, for a (100) silicon substrate 101,the semiconductor surface may be miscut, or offcut, for example 2-10degree. toward (110). In another embodiment, substrate 101 is (111)silicon with crystalline substrate surface region having hexagonalcrystallinity.

FIG. 2 is cross-sectional views illustrating an intermediate stage inthe formation of the semiconductor die structure 100, in accordance withsome embodiments of the present disclosure. In some embodiments, aplurality of silicon-containing lines 103 such as polysilicon lines maybe disposed or grown over the substrate 101. The silicon-containinglines 103 may include a pattern at twice the final pitch (e.g., pitch isthe width of a metal line plus the spacing between two metal lines) andcapped with a hard mask 107. The hard mask 107 may include SiN. Thesilicon-containing lines 103 may be patterned on SiN, SiC, or alumina. Aspacer layer 105 (e.g., silicon oxide) may be fabricated on thesilicon-containing lines 103. It may be noted that a buffer layer (notshown) may be disposed between the silicon-containing lines 103 andsubstrate 101. An appropriate buffer layer may be disposed correspondingto the material type of substrate 101.

FIG. 3 is a cross-sectional view illustrating an intermediate stage offorming a carbon hard mask 109 in the formation of the semiconductor diestructure 100, in accordance with some embodiments of the presentdisclosure. In some embodiments, the carbon hard mask 109 is formed onthe spacer layer 105 by the deposition process, and a mask opening 109Ais then formed in the carbon hard mask 109 by lithographicallypatterning.

FIG. 4 is a cross-sectional view illustrating an intermediate stage offorming a spacer opening 105A in the formation of the semiconductor diestructure 100, in accordance with some embodiments. In some embodiments,an etching process is performed to transfer the mask opening 109A intothe spacer opening 105A of the spacer layer 105.

FIG. 5 is a cross-sectional view illustrating an intermediate stage offorming the supporting backbone 111 in the formation of thesemiconductor die structure 100, in accordance with some embodiments ofthe present disclosure. In some embodiments, the supporting backbone 111may be fabricated by using a spin-on technique. The material of thesupporting backbone 111 can be a spin-on metallic oxide (tungsten oxide,hafnium oxide, or zirconium oxide) that is deposited only up to athreshold height. The supporting backbone 111 may be a spin-ondielectric that has Si—C—Si (e.g., not Si—O—Si) in the backbone and thatis properly cured to withstand hydrofluoric (HF) acid. In anotherembodiment, a non-conformal SiN, SiC, or SiCN may be used (e.g., insteadof a spin-on) which may leave a thin etch top layer on the oxide spacerand may help protect the metal barrier from the HF strip during thesubsequent air gap formation.

FIG. 6 is a cross-sectional view illustrating an intermediate stage offorming a conductor block 113 in the formation of the semiconductor diestructure 100, in accordance with some embodiments of the presentdisclosure. In some embodiments, the carbon hard mask 109 is removed(e.g., the carbon hard mask 109 is ashed away) and the conductor block113 fills the regions between the spacer layer 105. The conductor block113 may be a recessable material such as cobalt (Co), copper (Cu),ruthenium (Ru), or amorphous silicon (a-Si) (e.g., a-Si which issilicided later to form CoSi or NiSi).

FIG. 7 is a cross-sectional view illustrating an intermediate stage ofperforming a planarization process in the formation of the semiconductordie structure 100, in accordance with some embodiments of the presentdisclosure. At the step S13 in the method 10 shown in FIG. 1, a firstconductor block is formed on the first supporting backbone. In someembodiments, a planarization process such as a chemical mechanicalpolishing (CMP) process is performed to remove a portion of the metallayer 113, such that the spacer layer 105 is exposed. In someembodiments, after the planarization process, a plurality of conductorblocks 113A are embedded in the spacer layer 105, wherein the top endsof the conductor blocks 113A are substantially the same as that of thespacer layer 105.

FIG. 8 is a cross-sectional view illustrating an intermediate stage ofperforming a recessing process in the formation of the semiconductor diestructure 100, in accordance with some embodiments of the presentdisclosure. In some embodiments, a portion of the conductor blocks 113Ais removed by a recessing process such as an etching back process toform a plurality of conductor blocks 113B embedded in the spacer layer105, wherein the top ends of the conductor blocks 113B are lower thanthat of the spacer layer 105.

FIG. 9 is a cross-sectional view illustrating an intermediate stage offorming a metal silicide layer 113D in the formation of thesemiconductor die structure 100, in accordance with some embodiments ofthe present disclosure. In some embodiments, when the conductor block113C is a-Si, metal may be deposited on the conductor block 113C andannealed to form the metal silicide layer 113D over the conductor block113C. In some embodiments, metal nickel (Ni) may be deposited andannealed to form nickel silicide (NiSi) or metal cobalt (Co) may bedeposited and annealed to form cobalt silicide (CoSi).

FIG. 10 is a cross-sectional view illustrating an intermediate stage offorming a first hard mask 115 in the formation of the semiconductor diestructure 100, in accordance with some embodiments of the presentdisclosure. In some embodiments, a deposition process is performed toform the first hard mask 115 over the metal silicide layer 113D and aplanarization process is then performed on the first hard mask 115. Insome embodiments, the first hard mask 115 may include SiC, SiOC, ZrO2,HfO2, or W oxide. In some embodiments, the first hard mask 115 may beone or more of a dielectric, a carbide, or a metallic carbide. Afterforming the first hard mask layer 115, the conductor block 113C and themetal silicide layer 113D capped with the first hard mask 115 may bereferred to as a metal line or a wire.

FIG. 11 is a cross-sectional view illustrating an intermediate stage ofperforming an etching process in the formation of the semiconductor diestructure 100, in accordance with some embodiments of the presentdisclosure. In some embodiments, the hard mask 107 is removed to exposethe silicon-containing lines 103 by an etching process such as a dryetching process to selectively remove the hard mask 107, while remainingthe silicon-containing lines 103 on the substrate 101.

FIG. 12 is a cross-sectional view illustrating an intermediate stage ofperforming an etching process in the formation of the semiconductor diestructure 100, in accordance with some embodiments of the presentdisclosure. In some embodiments, the silicon-containing lines 103 areetching out to expose portions of the substrate 101, while remaining thespacer layer 105 on the substrate 101.

FIG. 13 is a cross-sectional view illustrating an intermediate stage ofperforming a deposition process in the formation of the semiconductordie structure 100, in accordance with some embodiments of the presentdisclosure. In some embodiments, the deposition process is performed todeposit material of the spacer layer 105 on at least the exposedportions of the substrate 101 and the first hard mask 115.

FIG. 14 is a cross-sectional view illustrating an intermediate stage offorming a second supporting backbone in the formation of thesemiconductor die structure 100, in accordance with some embodiments ofthe present disclosure. At the step S15 in the method 10 shown in FIG.1, a second supporting backbone 119 is formed on the substrate 101. Insome embodiments, similar to the fabrication processes described inFIGS. 3-5, a carbon hard mask 117 is formed on the spacer layer 105 bythe deposition process, and a mask opening 117A is then formed in thecarbon hard mask 117 by lithographically patterning. In someembodiments, an etching process is performed to transfer the maskopening 117A into a spacer opening of the spacer layer 105 to expose aportion of the substrate 101. Subsequently, the supporting backbone 119is then formed on the exposed portion of the substrate 101.

FIG. 15 is a cross-sectional view illustrating an intermediate stage offorming a conductor block 120 in the formation of the semiconductor diestructure 100, in accordance with some embodiments of the presentdisclosure. At the step S17 in the method 10 shown in FIG. 1, a secondconductor block 120 is formed on the second supporting backbone 119. Insome embodiments, similar to the fabrication processes described inFIGS. 6-9, the carbon hard mask 117 is removed (e.g., the carbon hardmask 117 is ashed away) and the conductor block 120 fills the regionsbetween the spacer layer 105. The conductor block 120 may be arecessable material such as cobalt (Co), copper (Cu), ruthenium (Ru), oramorphous silicon (a-Si) (e.g., a-Si which is silicided later to formCoSi or NiSi).

In some embodiments, a planarization process such as a chemicalmechanical polishing (CMP) process is performed to remove a portion ofthe conductor block 120, such that the spacer layer 105 is exposed. Insome embodiments, after the planarization process, the conductor block119 is embedded in the spacer layer 105, wherein the top end of theconductor block 120 is substantially the same as that of the spacerlayer 105. In some embodiments, a recessing process such as an etchingback process is then performed to remove a portion of the conductorblock 120, wherein the top end of the conductor block 120 issubstantially the same as that of the spacer layer 105.

In some embodiments, when the conductor block 120 is a-Si, metal may bedeposited and annealed to form a metal silicide layer 120D over theconductor block 120. In some embodiments, metal nickel (Ni) may bedeposited and annealed to form nickel silicide (Nisi) or metal cobalt(Co) may be deposited and annealed to form cobalt silicide (CoSi).

FIG. 16 is a cross-sectional view illustrating an intermediate stage offorming a second hard mask 121 in the formation of the semiconductor diestructure 100, in accordance with some embodiments of the presentdisclosure. In some embodiments, a deposition process is performed toform the second hard mask 121 over the metal silicide layer 120D and aplanarization process is then performed on the second hard mask 121. Insome embodiments, the second hard mask 121 may include SiC, SiOC, ZrO2,HfO2, or W oxide. In some embodiments, the second hard mask 121 may beone or more of a dielectric, a carbide, or a metallic carbide. Afterforming the second hard mask. 121, the conductor block 120 and the metalsilicide layer 120 capped with the second hard mask 121 may be referredto as a metal line or a wire.

FIG. 17 is a cross-sectional view illustrating an intermediate stage ofremoving the spacer layer 105 in the formation of the semiconductor diestructure 100, in accordance with some embodiments of the presentdisclosure. At the step S19 in the method 10 shown in FIG. 1, aplurality of suspended conductor blocks are formed over the substrateand connected to the first conductor block and the second conductorblock. In some embodiments, the spacer layer 105 removed to expose thesubstrate 101. In some embodiments, hydrofluoric (HF) cleanse may be ranto remove the spacer layer 105, while the first supporting backbone 111and the second supporting backbone 119 are not etched. A first set ofthe conductor block 113C and the conductor block 120 (e.g., metal lines,wires) are disposed on the first supporting backbone 111 and the secondsupporting backbone 119, while a second set of the conductor block 113Cand the conductor block 120 (e.g., metal lines, wires) are suspendedabove the substrate 101 between the first supporting backbone 111 andthe second supporting backbone 119.

FIG. 18 is a cross-sectional view illustrating an intermediate stage offorming an energy removable layer 123 and a capping dielectric layer 125in the formation of the semiconductor die structure 100, in accordancewith some embodiments of the present disclosure. At the step S21 in themethod 10 shown in FIG. 1, an energy removable layer and a cappingdielectric layer are sequentially formed over the substrate. In someembodiments, the energy removable layer 123 and the capping dielectriclayer 125 are sequentially formed over the substrate 101, in accordancewith some embodiments.

In some embodiments, the material of the energy removable layer 123includes a thermal decomposable material. In some other embodiments, thematerial of the energy removable layer 123 includes a photonicdecomposable material, an e-beam decomposable material, or anotherapplicable energy decomposable material. Specifically, in someembodiments, the material of the energy removable layer 123 includes abase material and a decomposable porogen material that is substantiallyremoved once being exposed to an energy source (e.g., heat).

In some embodiments, the base material includes hydrogen silsesquioxane(HSQ), methylsilsesquioxane (MSQ), porous polyarylether (PAE), porousSiLK, or porous silicon oxide (SiO2), and the decomposable porogenmaterial includes a porogen organic compound, which can provide porosityto the space originally occupied by the energy removable layer 123 inthe subsequent processes.

In addition, the capping dielectric layer 125 is made of silicon oxide,silicon nitride, silicon oxynitride, or multilayers thereof. In someembodiments, the capping dielectric layer 125 is made of a low-kdielectric material. In addition, the energy removable layer 123 and thecapping dielectric layer 125 may be formed by deposition processes. Insome embodiments, the deposition processes include chemical vapordeposition (CVD), physical vapor deposition (PVD), atomic layerdeposition (ALD), spin-coating, or another applicable process.

FIG. 19 is a cross-sectional view illustrating an intermediate stage offorming air gaps 127 and liner layers 129 in the formation of thesemiconductor die structure 100, in accordance with some embodiments ofthe present disclosure. At the step S23 in the method 10 shown in FIG.1, a heat treatment process is performed to transform the energyremovable layer into air gaps enclosed by liner layers. In someembodiments, a heat treatment process is performed to transform theenergy removable layer 123 into an air gap structure 130 including anair gap 127 and a liner layer 129 enclosing the air gap 127. In someembodiments, the heat treatment process is used to remove thedecomposable porogen materials of the energy removable layer 123 togenerate pores, and the base materials of the energy removable layer 123is accumulated at the edges of the energy removable layer 123 to formthe liner layers 129. The pores are filled by air after the decomposableporogen materials are removed, such that the air gaps 127 are obtainedinside the remaining portions of the energy removable layer 123. In someembodiments, the air gaps 127 may be a vacuum (e.g., pump out the gas inthe air gaps). In some embodiments, the air gaps 127 may include aninert gas (e.g., nitrogen, helium, argon, air, etc.).

In some other embodiments, the heat treatment process can be replaced bya light treatment process, an e-beam treatment process, a combinationthereof, or another applicable energy treatment process. For example, anultra-violet (UV) light or laser light may be used to remove thedecomposable porogen materials of the energy removable layer 123, andthe air gaps 127 is then obtained.

FIG. 20 is a schematic illustration of an exemplary integrated circuit,such as a memory device 1000, including an array of memory cells 30 inaccordance with some embodiments. In some embodiments, the memory device1000 includes a dynamic random access memory (DRAM) device. In someembodiments, the memory device 1000 includes a number of memory cells 30arranged in a grid pattern and including a number of rows and columns.The number of memory cells 30 may vary depending on system requirementsand fabrication technology.

In some embodiments, each of the memory cells 30 includes an accessdevice and a storage device. The access device is configured to providecontrolled access to the storage device. In particular, the accessdevice is a field effect transistor (FET) 31 and the storage device is acapacitor 33, in accordance with some embodiments. In each of the memorycells 30, the FET 31 includes a drain 35, a source 37 and a gate 39. Oneterminal of the capacitor 33 is electrically connected to the source 37of the FET 31, and the other terminal of the capacitor 33 may beelectrically connected to the ground. In addition, in each of the memorycells 30, the gate 39 of the FET 31 is electrically connected to a wordline WL, and the drain 35 of the FET 31 is electrically connected to abit line BL.

The above description mentions the terminal of the FET 31 electricallyconnected to the capacitor 33 is the source 37, and the terminal of theFET 31 electrically connected to the bit line BL is the drain 35.However, during read and write operations, the terminal of the FET 31electrically connected to the capacitor 33 may be the drain, and theterminal of the FET 31 electrically connected to the bit line BL may bethe source. That is, either terminal of the FET 31 could be a source ora drain depending on the manner in which the FET 31 is being controlledby the voltages applied to the source, the drain and the gate.

By controlling the voltage at the gate 39 via the word line WL, avoltage potential may be created across the FET 30 such that theelectrical charge can flow from the drain 35 to the capacitor 33.Therefore, the electrical charge stored in the capacitor 33 may beinterpreted as a binary data value in the memory cell 30. For example, apositive charge above a threshold voltage stored in the capacitor 33 maybe interpreted as binary “1.” If the charge in the capacitor 33 is belowthe threshold value, a binary value of “0” is said to be stored in thememory cell 30.

The bit lines BL are configured to read and write data to and from thememory cells 30. The word lines WL are configured to activate the fieldeffect transistors (FET) 31 to access a particular row of the memorycells 30. Accordingly, the memory device 1000 also includes a peripheryregion which may include an address buffer, a row decoder and a columndecoder. The row decoder and the column decoder selectively access thememory cells 30 in response to address signals that are provided to theaddress buffer during read, write and refresh operations. The addresssignals are typically provided by an external controller such as amicroprocessor or another type of memory controller.

Referring back to FIG. 19, the air gaps 127 are formed in the cellregion 300 (i.e., the pattern-dense region) of the semiconductor diestructure 100, while no air gap is formed in the peripheral region 400(i.e., the pattern-loose region) of the semiconductor die structure 100.

Embodiments of the semiconductor die structure 100 are provided in thedisclosure. The semiconductor die structure 100 includes a plurality ofair gaps 127, and the conductor block 113C and the conductor block 120are separated from the each other by the air gaps 127. Therefore, theparasitic capacitance between the conductive contacts may be reduced. Asa result, the overall device performance may be improved (i.e., thedecreased power consumption and resistive-capacitive (RC) delay), andthe yield rate of the semiconductor device may be increased.

One aspect of the present disclosure provides a semiconductor diestructure, comprising: a substrate; a first supporting backbone disposedon the substrate; a second supporting backbone disposed on thesubstrate; a first conductor block disposed on the first supportingbackbone; a second conductor block disposed on the second supportingbackbone; a third conductor block disposed above the substrate andconnected to the first conductor block and the second conductor block;and an air gap structure disposed between the first conductor block, thesecond conductor block, and the third conductor block, wherein the airgap structure comprises an air gap and a liner layer enclosing the airgap.

Another aspect of the present disclosure provides a semiconductor diestructure, comprising: a substrate including a first site and a secondsite; a first conductor block disposed on the first site; a secondconductor block disposed on the second site; a third conductor blockdisposed above the substrate and connected to the first conductor blockand the second conductor block; an air gap structure disposed betweenthe first conductor block, the second conductor block, and the thirdconductor block, wherein the air gap structure comprises an air gap anda liner layer enclosing the air gap.

Another aspect of the present disclosure provides a method for preparinga semiconductor die structure, comprising: forming a first supportingbackbone on the substrate; forming a first conductor block on the firstsupporting backbone; forming a second supporting backbone on thesubstrate; forming a second conductor block on the second supportingbackbone; forming a third conductor block suspended above the substrateand connected to the first conductor block and the second conductorblock; sequentially forming an energy removable layer and a cappingdielectric layer over the substrate, and the energy removable layer andthe capping dielectric layer separating the first conductor block, thesecond conductor block and the third conductor block; and performing aheat treatment process to transform the energy removable layer into aplurality of air gap structures, wherein at least one of the air gapstructures comprises an air gap and a liner layer enclosing the air gap.

Although the present disclosure and its advantages have been describedin detail, it should be understood that various changes, substitutionsand alterations can be made herein without departing from the spirit andscope of the disclosure as defined by the appended claims. For example,many of the processes discussed above can be implemented in differentmethodologies and replaced by other processes, or a combination thereof.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present disclosure, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein, may be utilized according tothe present disclosure. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, and steps.

What is claimed is:
 1. A semiconductor die structure, comprising: asubstrate; a first supporting backbone disposed on the substrate; asecond supporting backbone disposed on the substrate; a first conductorblock disposed on the first supporting backbone; a second conductorblock disposed on the second supporting backbone; a third conductorblock disposed above the substrate and connected to the first conductorblock and the second conductor block; and an air gap structure disposedbetween the first conductor block, the second conductor block, and thethird conductor block, wherein the air gap structure comprises an airgap and a liner layer enclosing the air gap.
 2. The semiconductor diestructure of claim 1, further comprising a first metal cap disposed onthe first conductor block and a second metal cap disposed on the secondconductor block.
 3. The semiconductor die structure of claim 2, whereinthe first metal cap and the second metal cap comprise a metal silicide.4. The semiconductor die structure of claim 3, wherein the metalsilicide comprises cobalt (Co), copper (Cu), ruthenium (Ru), cobaltmonosilicide (CoSi), or nickel mono-silicide (NiSi).
 5. Thesemiconductor die structure of claim 1, wherein the third conductorblock is suspended over the air gap structure.
 6. The semiconductor diestructure of claim 1, wherein the first conductor block and the secondconductor block are separated by the air gap structure.
 7. Thesemiconductor die structure of claim 1, wherein the first supportingbackbone and the second supporting backbone are separated by the air gapstructure.
 8. The semiconductor die structure of claim 1, wherein thefirst supporting backbone and the second supporting backbone comprise atungsten oxide, a hafnium oxide, a zirconium oxide, silicon mononitride(SiN), silicon carbide (SiC), silicon carbonitride (SiCN).
 9. Asemiconductor die structure, comprising: a substrate including a firstsite and a second site; a first conductor block disposed on the firstsite; a second conductor block disposed on the second site; a thirdconductor block disposed above the substrate and connected to the firstconductor block and the second conductor block; an air gap structuredisposed between the first conductor block, the second conductor block,and the third conductor block, wherein the air gap structure comprisesan air gap and a liner layer enclosing the air gap.
 10. Thesemiconductor die structure of claim 9, further comprising a first metalcap disposed on the first conductor block and a second metal capdisposed on the second conductor block.
 11. The semiconductor diestructure of claim 10, wherein the first metal cap and the second metalcap comprise a metal silicide.
 12. The semiconductor die structure ofclaim 11, wherein the metal silicide comprises cobalt (Co), copper (Cu),ruthenium (Ru), cobalt monosilicide (CoSi), or nickel mono-silicide(NiSi).
 13. The semiconductor die structure of claim 9, wherein thethird conductor block is suspended over the air gap structure.
 14. Thesemiconductor die structure of claim 9, wherein the first conductorblock and the second conductor block are separated by the air gapstructure.
 15. A method for preparing a semiconductor die structure,comprising: forming a first supporting backbone on the substrate;forming a first conductor block on the first supporting backbone;forming a second supporting backbone on the substrate; forming a secondconductor block on the second supporting backbone; forming a thirdconductor block suspended above the substrate and connected to the firstconductor block and the second conductor block; sequentially forming anenergy removable layer and a capping dielectric layer over thesubstrate, and the energy removable layer and the capping dielectriclayer separating the first conductor block, the second conductor blockand the third conductor block; and performing a heat treatment processto transform the energy removable layer into a plurality of air gapstructures, wherein at least one of the air gap structures comprises anair gap and a liner layer enclosing the air gap.
 16. The method of claim15, wherein the forming of the first supporting backbone on thesubstrate comprises: forming a plurality of silicon-containing lines onthe substrate; depositing a spacer layer on the substrate and theplurality of silicon-containing lines; and removing a first portion ofthe spacer layer to expose a first portion of the substrate between theplurality of polysilicon lines.
 17. The method of claim 15, wherein theforming of the first conductor block on the first supporting backbonecomprises forming a metal capped with a first hard mask between theplurality of silicon-containing lines.
 18. The method of claim 17,wherein the forming of the second supporting backbone comprises:removing the plurality of polysilicon lines; forming the spacer layer onthe substrate; and removing a second portion of the spacer layer toexpose a second portion of the substrate.
 19. The method of claim 18,wherein the forming of the second conductor block on the secondsupporting backbone comprises forming the metal capped with a secondhard mask.
 20. The method of claim 19, wherein the forming of the thirdconductor block above the substrate further comprises removing thespacer layer.